1. Field of the Invention
The present invention relates to a bolt anchoring device, particularly to an expansible anchor assembly and its adapted fastening device.
2. Description of the Related Art
FIGS. 1 and 2 disclose a conventional expansible anchoring device 1. The anchoring device 1 includes an expansion sleeve 11 and an anchor bolt 12 extending through the expansion sleeve 11 for an expansion. Wherein, the expansion sleeve 11 includes a receiving end 111, an abutting end 112 to contact with a surface of the wall, and an expansible portion 113 having multiple slots 1131 extending from the abutting end 112 and dividing the portion 113 into expansible segments 1132 disposed adjacent to the abutting end 112, and a bore 114 defined within the expansion sleeve 11 for communicating the receiving end 111 with the abutting end 112. Further, an inner wall of the sleeve 11 has a threaded portion 1141 disposed close to the receiving end 111, a propelling leg 1142 disposed close to the abutting end 112, and a supporting portion 1143 disposed between the threaded portion 1141 and the propelling leg 1142. The propelling leg 1142 is formed into a cone shape tapered from the supporting portion 1143 toward the abutting end 112. In addition, the anchor bolt 12 includes a plug body 121 for extending through the supporting portion 1143 and an insert 122 extending outwardly from the plug body 121 for abutting with respect to the propelling leg 1142.
Referring to FIG. 3, in operation, the expansion sleeve 11 of the anchoring device 1 is subjected to a knocking force and plugged a pre-drilling hole 21 of a wall 2 so as to fix the anchoring device 1 therein. Further, the insert 122 of the anchor bolt 12 thence moves toward the propelling leg 1142 when users use a tool (not shown) to axially push the plug body 121 through the bore 114 of the sleeve, with the result that the expansible portion 113 subjected to an outward expansion force makes the expansible segments 1132 expanded to maintain the anchoring force. Then, a screw 3 could be screwed along the threaded portion 1141 for accomplishing the installation of the anchoring device 1.
Generally, the expansible portion 113 along with the slits 1131 is prolonged for which to be efficiently expanded under the pushing force of the anchor bolt 12. It is because the anchor bolt 12 easily lacks sufficient moment force and fails to completely widen the expansible segments 1132 of the portion 113 in case the expansion portion 113 is designed quite shorter. In contrast, the expansion portion 113 designed quite longer as shown in the aforementioned convention configuration may allow the anchor bolt 12 to successfully expand the expansion portion 113, but at the beginning when the portion 113 starts to expand, the expansion turns to direct against the hole 21, which restricts the pursuing expanding and renders the expansion portion 113 unable to be spread as dotted in FIG. 3, namely the dimension of the expansion is diminished and hence the anchoring force of the device 1 is influenced. If the expansion portion 113 is otherwise over-expanded, the pre-drilled hole 21 would be subjected to a huge pressure, which however results in breaking or damaging the wall 2 during operation and decreasing the anchoring force. To a practical experiment, as it is the anchoring device 1 can only be slightly but not thoroughly expanded even though the anchor bolt 12 bears a huge knocking force.
Still further, when the user pushes and directs the anchor bolt 12 against the propelling leg 1142, he or she cannot exactly judge whether the anchor bolt 12 is completely plugged in the propelling leg 1142 or not, instead, they merely determine in light of their experiences. The expansible portion 113 is over lengthened, with the result that the user usually cannot be successful in expecting the propelling or anchoring journey of the anchor bolt 12 destined for the propelling leg 1142. In such a situation, the anchor bolt 12 fails to widen the propelling leg 1142 completely, which results in decreasing the anchoring force of the expansible portion 113, even deteriorating or fading away the anchoring force in case that the anchor bolt 12, which does not completely rest against the propelling leg 1142, is subjected to any external vibration and thus slipped out of the propelling leg 1142. Therefore, the fixing effect is easily affected.
Furthermore, in view of the over-length expansible portion 113 along with the prolonged slots 1131 and the propelling leg 1142 in a cone shape, if an overlarge force imposed on the cutting of the slots 1131 would easily render the slots to lose a support and become deformed during cutting of the manufacture, which however increase the difficulty of shaping by relevant cutting tools.